Arc-welding apparatus



March 19, 1963 F. E. ADAMsoN ETAL 3,082,317

ARC-WELDING APPARATUS Filed Aug, 30, 1960 4 Sheets-Sheet 1 Floyd E. Adamson 8x 9@ "KW Roger R. Gler March 19, 1963 F. E. ADAMsoN ETAL. 3,082,317

ARC-WELDING APPARATUS Filed Aug. 30. 1960 4 Sheets-Sheet 2 UNIT March 19, 1963 F. E. ADAMsoN ETAL 3,082,317

ARC-WELDING APPARATUS Filed Aug. 50, 1960 4 Sheets-Sheet 4 Sl-IOA O O O 1' N O United States Patent O r 3,082,317 ARC-WELDING APPARATUS f Floyd E. Adamson, Kenmore, and Roger R. Giler, East Aurora, N.Y., assignors to Westinghouse Electrlc Corporation, East Pittsburgh, Pa., a corporation of Penu- Sylvania Filed Aug. 30, 1960, Ser. No. 52,842 12 Claims. (Cl. 219-130) This invention relates to the arc-Welding art and has particular relationship to arc-welding apparatus of the consumable-electrode type in which a portable welding gun generally as disclosed in Patent 3,038,990 granted .lune 12,1962, to George H. Cotter and Harry I. Bichsel for Arc-Welding Apparatus is used. Application Serial No. 202,716 iiled June l5, 1962, is a division of this application. The gun disclosed in the Cotter-Bichsel patent includes a motor mounted in the gun for advancing an electrode from a reel mounted on the gun to the arc between the electrode and the work -through a nozzle. The gun is used with a power-supply unit which supplies the power to the welding arc and with a control unit which controls the iiow of welding current to the gun, the flow of shielding gas through the gun and the operation of the gun motor and the other components. The powersupply unit and the control unit are in separate containers which may be separated a substantial distance from the gun. In a typical situation the gun may be used by an operator on the mast of a ship and the connections between the gun and the power-supply unit and the control unit are cables which may be 50 to 250 feet long.

The demand has arisen for such guns and controls in installations in which either direct current or alternating current may be provided. In such installations, the power-supply unit is energized independently of the control unit and is usually of the direct current type but could be of the alternating current type with suitable modiiications of the controls. The control unit is connected to control or auxiliary supply buses which may supply either alternating current or direct current through an unpolarized connector. This connection on the control unit side of the connector must be direct and not through a transformer electrically insulating the buses from the control unit.

It is an object of this invention' to provide welding apparatus including a universal control unit capable of operating either from a direct-current or an alternatingcurrent supply and capable of being connected to this supply through an unpolarized connector.

In accordance with this invention in one of its specilic aspects the control unit is supplied through a bridge rectifier. This rectifier has opposite branches in each of which one or more rectifying elements are connected and which define opposite conjugate terminals. One pair of terminals which may be called input terminals are connected to the connector which is connected to the control buses. The other conjugate terminals which may be called output or direct-current terminals are connected to the components of the control unit. When the control supply is of the alternating-current type the bridge provides direct current at its output terminals. When this supply is of the direct-currenti`type the power to the control components is supplied through one setof arms when the connector is plugged in, in one sense and through the other set of arms when the connector is plugged in in the opposite sense.

In accordance with the specific aspects of this invention the rectifier elements in the arms are of the silicondiode type. The expression silicon-diode is used here with the understanding that'it may cover'any low-forward resistance, high-back-resistance, rectifying component whether it be composed of the element silicon or the 3,082,317 Patented Mar. 19, 1963 element germanium or of a like element. A rectifier bridge of the silicon-diode type with high back resistance has the advantage that the back current through the relays and other components of the control unit is a minimum and these components are effectively energized and actuated. ln addition, silicon-diode rectifiers themselves, are capable of operating at relatively high ambient temperatures.

In the use of the apparatus disclosed here the power supply unit for energizing the welding arc may be of the constant-current type in which the arc current is approximately constant and the voltage varies with the length of the arc. In apparatus in which the power-supply unit is of the constant current type the motor is connected across the arc during operation. During standby it is desirable that the motor be connected to the control unit so that inching of the electrode may readily be carried out.

A specific aspect of this invention arises from the discovery that short-circuiting of the control supply buses must be prevented where the control unit is of the A.C.- D.C. type and it is aspeciiic object otl this invention to prevent such grounding. It has been realized that at the usual site of a welding operation one of the control supply buses may be grounded. Since the Work is also grounded short-circuiting occurs, if either of the direct-current terminals of the rectifier bridge is permitted to be connected to the work while the buses are connected to what are usually regarded as the alternating current terminals of the bridge.

lIn accordance with this invention, switch means are provided which maintain the direct-current terminals of the rectifier bridge disconnected from the work, both during the stand-by condition of the apparatus and during the operating condition of the apparatus. Essentially this switch means controls the connections of the electrode motor during stand-by when the motor is set for inching and during operation when the motor is setto advance the electrode towards the work for arc welding. In accordance with the specic aspectsV of this invention the switch means includes a back contact and a front contact of the starting relay which is actuated to cause the apparatus to pass from stand-by to operation. The back contact in the unactuated condition of the relay connects the terminal of the motor to be connected to the work to one of the direct-current terminals of the bridge and the front contact disconnects this terminal from the work. During operation the starting relay is actuated and the above-mentioned terminal of the motor is disconnected from the terminal of the bridge by the back contact and connected to the work by the front contact.

In early use of the apparatus disclosed herein it was found that the motor had a tendency to have a relatively short life. It is a specific object of this invention to provide apparatus of the type just disclosed in which the motor shall have a relatively long life.

rThis aspect of this invention arises from the discovery that the shortness of the life of the motor has several principal causes. An important factor in shortening the lire of the motor is the surge which is produced during a welding operation when the operator without releasing the gun trigger, which is the starting switch, abruptly removes the electrode from the work interrupting the arc. It has been discovered that in the case of apparatus which does not embody this invention the removal of the electrode from the work and the interruption of the arc without releasing the trigger may result in an impulse of several hundred volts between the brushes across the armature of the motor. 'This coulddamage the insulation ofthe armature. The motor life is also shortened by the relatively high frequency voltage, or hash, which is impressed on the armature through the brushes when the motor is connected across the arc during a welding apagar? Y 3 operation. The hash is produced both by the welding arc and by the commutation sparking at the brushes of the motor.

It has been found that the amplitude of the impulse produced when the electrode is removed from the work may be reduced by a factor of as much as l() by connecting a relatively small capacitor directly between the brushes of the motor but the impulse which is now produced by withdrawal of the electrode from the work with the trigger closed has been found to have considerable hash. vIn accordance with this invention the hash is suppressed by a large capacitor connected across the conductors which are connected to the motor from the control unit and the power-supply unit at a point remote from the motor itself. It has been found that the life of the motor in apparatus in accordance with this invention in which a large capacitor is so connected is increased by 100%.

In the usual practice'of this invention the arc is connected to the control unit by a long cable and to provide the energizing potential for the motor there are long conductors from the control unit back to the motor which is near' the arc. The large capacitor is connected at the control unit between the conductors which are connected to the motor and the conductors which are connected to the arc.

In yaddition to its electrical advantages the mounting of the large capacitor at or near the control unit has the advantage of not affecting the flexibility of the gun. The capacitor usually has a capacitance of several hundred microfarads and while it may be an electrolytic capacitor it is relatively large. Such a capacitor mounted on the gun would materially impede the handling of the gun.

.While the small capacitor has advantages in the preferred practice of this invention, this invention in its broader aspects may be practiced with the large capacitor connected at or near the control unit above.

A further aspect of this invention arises from the discovery that the diodes of the rectifier bridge are damaged by high surges produced during transitions in the welding operation. The cause of the surges was found to be the inductance of the contactor and gas valve solenoids in the circuit. In accordance with this invention the surges were suppressed by properly decreasing the ohmic resistance in the circuit with the solenoids.

The novel features considered characteristic of this invention are disclosed generally above. The invention itself both as to its organization and as to its method of operation together with additional objects and advantages thereof will ,be understood from the following description of a specic embodiment ltaken in connection with accompanying drawings, in which:

FIGURE l is a block diagram showing a preferred embodiment of this invention;

FIGURE 2 is a schematic of the embodiment of the invention shown in FIG. l;

FIGURE 3 are oscillograms of the wave form across the brushes of the electrode motor in apparatus in accordance with this invention produced during welding when the operator interrupts the arc by removing the gun from the work with the starting switch closed;

FIGURES 4 and 5 are oscillograms under like conditions produced with apparatus not incorporating certain of the features of this invention;

FIGURE 6 are oscillograms ot the wave form of the ripple produced across the brushes of the electrode gunV during inching under different conditions;

FIGURE 7 are oscillograrns showing the surges produced across the diodes of the rectifier bridge in apparatus not incorporating certain of the features of this invention during the transition from the operating condition of the apparatus to the stand-by condition; and

FIGURE 8 are like oscillograms produced during the transition from the operation condition to stand-by with apparatus in accordance with this invention.

The apparatus shown in the drawings includes a Gun, a Power-Supply Unit for supplying power to the arc during a welding operation and a Control Unit for controlling the operation of the Gun and the Power Supply Unit. In the preferred practice of this invention the Gun, the Power Supply Unit and the Control Unit are three physically separate units interconnected by conductors 11, 13 and 17 and cable 15 for transmitting current and a tube i9 for shielding gas. The contactor 1M which controls the Power Supply Unit is in a separate cabinet or container. Typically this contactor may be a Westinghouse MM410.

he Power-Supply Unit has a'grounded terminal 101 and a hot terminal 103. The terminal .lill is connected to ground conductor 17; the hot terminal 103 is adapted lto be connected to conductor 11 through contact lMa of contactor 1M.

Conductor 13 is connected to conductor 11 through coil `sCR of a current relay and extends from the Con-V trol Unit to the Gun. The potential from the Power Supply Unit is impressed on the electrode E through conductors 1f1 and 13 and Contact 1Ma. The bus 15 carries a number of conductors 5t); 51, 52, 53,54 and 56 from the Control `Unit to the Gun. The conductor 17 is the grounding conductor between the Power-Supply Unit and the work W; This conductor 17 is connected to the grounded terminal of the Power-Supply Unit and may be an ordinary conducting plate disposed on the deck of a ship. The tube 19 for the gas is connected from a Gas Supply through a valve controlled by solenoid SG in the Control Unit to the gas channel on the Gun.V The conductors 13, the cable 1S and the gastube 19` may be of substantial length, 50 to 25() feet, in the usual practice of this invention. The conductors 11 and 17 may be relatively long depending on the relative disposition of the Power-Supply Unit and the Control Unit.

The Power-Supply Unit may be of any suitable type,

for example, a direct-currentV generator powered by a gas engine or a rectifier welding unit such as a Westinghouse RA welding supply. In accordance with the speciic aspects of this invention the Power-Supply Unit is of the so-called constant current variable voltage type and in its specific aspects this invention is intimately tied in with Such a Power-Supply Unit. In accordance with the broader aspects of this invention the Power Supply Unit may be of a variable-current constantevoltage type such as the Westinghouse RCP welding supply.

The Gun preferably is of the general type disclosed in application Serial No. 690,526 and includes a channelV for transmitting an electrode E and shielding gas and a reel support carrying a relatively small electrode reel RE. The Gun also includes a'rnotor M mounted in the handle for advancing the electrode E to the 'work W. The Gun has a starting switch SW and an inching switch Sl which may be actuated readily by the operator.

A capacitor 1C is connected between the brushes of the motor M on the Gun. This capacitor 1C may have a capacity of about .05 microfarad and its principal purpose is to reduce surges and to prevent induced high lfrequency either from the arc or from neighboring equipment Ifrom being conducted through the windings of the motor M.

The contactor 1M is usually mounted on or near the Power-Supply Unit. This contactor 1M has a Vfront contact 1Mo which energizes the conductor `11 rendering this conductor cap-able of supplying power for arc welding between the electrode E and the workv W. A

resistor R4 (FIG. 2) is connected across the coil of thev Silicon diode D1, D2, D3, D4 respectively is connected. One set of opposite conjugate terminals 39 and 41 of the bridge lRX are the input terminals to the bridge and conductors L1 and L2 are respectively connected to these input terminals 39 and 41. r)The other opposite conjugate terminals 43 and 45 are the direct-current output terminals of the bridge and supply direct-current power to the Control Unit regardless of whether the input power is alternating current or direct current. The terminals 43 and 45 respectively, are connected to conductors DLI; and -DLZ from which direct current power is derived for the Control Unit.

The Control Unit also includes a gas solenoid for controlling the tlow of gas to the Gun, relay ZCR, relay 4CR and the current relay 3CR. The relay ZCR has front contacts ZCRa, 2CRd and ZCRe, and back contacts ZCRb and ZCRC. The relay 4CR has -front contacts 4CRa.

The solenoid of the current relay SCR consists of about 5 turns of the conductor extending from conductor 11. The relay SCR has a front contact SCRa. Because the relay 3CR has a substantial number of turns, the ampere turns produced when welding current ows through the coil of relay 3CR are high and the relay operates to close SCR at a relatively high speed.

The coil of contacter 1M and the solenoid of the gas valve SG are adapted to be connected Ibetween conductors DLl and DL2. through contact ZCRa. This contact is shunted by a capacitor 3C which typically may have a capacity of about .t0-5 microfarad.

The coil of relay ZCR is adapted to be connected between conductors DLI and DLZ through the starting switchSW. The 4coil of relay 4CR is adapted to be connected between conductors DLI and DLZ through the inching switch SI. The conductors DL and DL2 are adapted to be connected across a variable resistor 2R and a xed resistor 1R through the front Contact 4CRa and the back contact CRc. The resistor 2R is set to supply the motor M with relatively low voltage for inching. One terminal of the motor M is connected to the arm of resistor 2R through back contact ZCRb, the other terminal of the motor is connected to conductor DL?. through back contact ZCRC. When back contacts ZCRb and ZCRC are open the motor is disconnected lfrom DLZ and lfrom DLl.

'Ille terminal of the motor rM which is connected to 2CRb is also adapted to be connected to the junction of conductor 11 and the coil of relay SCR through front Contact ZCRe, a low resistor 3R, which typically may be 5 ohms, front contact SCRa and a variable resistor 1P which may have a resistance of between 25 and 50 ohms. The other terminal of the motor M is adapted to be connected to the work W through front contact ZCRd. The Control Unit includesa capacitor 2C which typically may have a capacitance of 30() microfarads. This capacitor 2C is connected across the terminals of the motor M at the Control Unit.

For convenience in understanding the invention involved here the long conductors are labeled LC in HG. 2.

' In the stand-by condition of the apparatus the connector .PU is connected to the supply conductors and conductors L1 and L2 are energized. Whether the supply buses are of the alternating-current or direct-current type conductors DL1 and DLZ are supplied fwith direct current. It the conductors are of the alternating current type the rectifier lRX rectitiesthe alternating potential supplied. If the buses `supply direct current then the rectifier l-RX passes the direct current. The rectifier lRX transmits the direct current regardless of the manner in which the connector PU is plugged in. lf PU is plugged in so that L1 is positive and L2 is negative the direct current ows through diodes D1 and D3 and if L2 is positive and D4.

entirely suppressed.

In the facilities in which the apparatus in accordance -With this invention is customarily used one or the other of the supply buses may be grounded. Regardless of which bus is grounded the ungrounded bus is connected to DLZ during each half period when it is negative, for example, assume that the buses supply alternating current and that the conductor L1 is connected to the ungrounded bus. Under such circumstances the ungrounded bus is eriodically connected to DLZ through diode D2 when L1 is electrically negative. If the buses supply direct current, the connector PU may be inserted so that the ungrounded bus is also connected to DLZ through one or the other of the diodes D2. or D3.

During stand-by buttons SW and SI are open and relays ZCR and 4CR are deenergized. Contactor 1M is also deenergized, Contact lMa is then open and conductor 11 is deenergized, Contact ltlCRa is open and the motor M is deenergized, contact 2CRc is closed but the short cir cuiting of the power buses to ground through the work 1V and D2. or D3 is prevented by contact ZCRd which is open.

Preparatory to a welding operation the electrode E is threaded through the gun and is properly positioned by an inching operation. For this purpose the inching button Sl is closed actuating relay l4CR. Potential is then applied to the motor M through contacts 4C'Rcz, ZCRb and ZCRC. ln `this case the motor is connected in energizing relationship with the buses of the supply but the buses are disconnected from the work at normally open front contact ZCRd.

During a welding operation the push-button SW is closed. The closing of pushbutton SW `actuates relay ZCR, opening ZCRC and ZCRb .and closing ZCRe and ZCRd. The conductor which was connected to ZCRc is now grounded at the work W but the ,grounding of DLZ and the shortcircuiting of the supply is prevented because ZCRC is open. The actuation of 2CR also actuates ZCRa energizing the gas solenoid SG and the contactor 1M. 1Ma is then closed energizing conductor 11 and gas is supplied through the Gun.

To start a welding operation the work Wis scratched by the electrode E firing an arc, relay SCR is then applied with current and contact SCRL: is closed. Potential is then supplied to the motor M from the arc between the electrode E and the work W and the motor rotates feeding rthe electrode E into the arc Iand making the weld deposit.

` Dur-ing the `welding operation the operator may remove the electrode from the work interrupting the arc while still maintaining the push-button SW, closed. Under such circumstances contact y1Mo remains closed and a surge may be impressed across the motor; this would tend to seriously damage the motor. FIG. 4 shows oscillograms showing a surge of the type here discussed produced with apparatus in which neither the capacitor 1C, connected directly across the motor Mnor the capacitor 2C connected across the motor M at the Control Unit is in eluded. As shown in the upper Ioscillogram'of FIG. 4, thesurge may be as high as 40() volts. The motor M subjected to this voltage would have a very short life. FIG. 5 shows oscillograms showing the wave form under the same conditions, that is when the operator. extinguishes the arc by removing the electrode from the work with the push-button SW closedLbut with the capacitor 1C connected directly across the motor M. In this case the surge is reduced to about 40 volts but as appears from the fuzziness of the oscillotgram thepotential impressed has a very irregular wave form including so-called hash. This wave form would tend to damage the brushes'. p

FIG. 3 shows oscillograrns showing the potential across the moto-r M in tappanatus in accordance with this invention when the operator extinguishes the arc by removing the electrode E from the work W with the switch SWy closed. In this ease a relatively Ilow voltage appears across the motor and the hash which appears in FIG. 5 is abonar? FIG. 6 shows the effects of the capacitors 1C .and 2C `on the wave form of the potential across the motor set for inching. The wave in these oscillograms corresponds to the 120 cycle ripple which is superimposed on the direct current derived through the rectifier lRX when the supply is of the 60 cycle alternating-current type. Oscillogram a shows the wave form of the potential across the motor M with both capacitors 1C and 2C absent. In this case the wave form is highly irregular and would be relatively rich in harmonics. Curve b is an oscillogram of the voltage across the motor with only capacitor 1C connected across the motor terminals. A slight improvement is achieved by including capacitor IC. Curve c is an oscillograrn of the voltage `across the motor M with both capacitor `1C and capacitor 2C included in the apparatus. In this case the wave form is smooth.

The oscillograms FIGS. 3 through 6 show that the capacitors 1C and 2C are essential in supporting the various undesired disturbances which would damage the motor M. The motor is during the major portion of its `operation energized from the arc potential, the arc is a highly irregular electrical phenomenon having a highly irregular wave form rich in harmonics of high frequency. The capacitors 1C and 2C suppress these higher harmonics thus preventing damage to the motor. In addition, capacitor 1C suppresses any neighboring high frequency signals which could' be induced across the motor.

The changing and discharging current for capacitor 2C derived Ifrom the arc potential flows along the long conductor between the electrode E and the coil of the relay ZCR and is impressed across the capacitor 2C essentially at the end of this long conductor. The potential from the arc is impressed across motor M through additional long conductors 511 and 53 which extend from capacit-or 2C to the motor. Essentially then there is substantial distributed inductance and capacitance between the arc and the capacitor 2C and additional substantial distributed inductance and capacitance between the capacitor 2C and the motor M.

The resistor R4 suppresses the surge produced by the coils of 1M and SG when the contacts ZCRa are opened. This is illustrated in FIGS. 7 and 8. FIG 7 is an oscillogram showing the back potential across the rectifier lRX in `apparatus not including resistor R4 when the contact ZCRa is opened after an operation. The surge produced may be as high as 1000 volts. This would tend to damage or destroy diodes D1 through D4. The surge is suppressed essentially by reducing the -ohmic resistance across 'the coil of contacter 1M and solenoid SG. The ef'Iect of the resistor R4 may be Iachieved by providing a high resistance contactor coil. In the usual situation this is not practicable; instead a resistance R4 is connected across the solenoids. lin a typical situation where the contactor 1M is a Westinghouse MM410 the resistor R4 may be one thousand ohms.

The effect of the resistor R4 is shown in FIG. 8 which presents oscillograms of the potential across the rectifier 1RX when contact ZCRa is open produced with apparatus in accordance with this invention. In this case the potential does not rise appreciably above the supply potential. y

The capacitor 2C suppresses arcing at the Vcontacts ZCRa when they are opened.

While in accordance with the specific aspects of this invention both capacitors are essential and perform important functions, the capacitor 2C can in many situations in accordance with the broader aspects of this in-` vention operate highly effectively to suppress most of the disturbances which could damage the motor. Apparatus including only capacitor 2C and not capacitor 1C is then within the scope of the broader aspects of this invention.

While a preferred embodiment of this invention has been disclosed herein many modifications thereof` are feasible. While this invention is disclosed herein as used in arc welding, arc melting is within the scope of the broader aspects of this invention to the extent that this invention is applicable thereto. The scope of this invention in its broader aspects also extends to 4arc welding in which the arc is produced between a non-consumable electrode andthe work and ra filler is supplied by motor M. This invention then is not 'to be restricted except insofar as is necessitated by the spirit lof the prior art.

We vclaim as our invention:

l. Apparatus for arc welding or arc melting work with a consumable electrode, comprising a power supply for said arc, means connected to said supply for impressing a potential between said electrode and work for producing an arc therebetween, a motor to be connected to said electrode for advancing said electrode into arc-welding relationship with said work, conductors of substantial length connected to said motor for connecting said arc in energizing relationship with said motor, a first capacitor connected between said conductors near their ends adjacent said motor, and a second capacitor having a capacitance large compared to the capacitance of said first capacitor connected between said conductors near their ends remote from said motor.

2. A drive to be energized from an alternating current supply including a direct current motor, rectifier means having input terminals connected to said Supply and direct current output terminals, conductors of substantial length connecting said direct current terminals in energizing relationship with said motor, a first capacitor connected between said conductors near their ends adjacent said motor, and a second capacitor having a capacitance large compared to the capacitance of said `first capacitor connected between said conductors near their ends adjacent said direct current terminals.

3. Apparatus for arc Welding or arc melting work with a consumable electrode comprising a Welding gun in-V cluding a motor in said gun for advancing said electrode through said gun, said motor having supply terminals, a power-supply unit for said arc, a control unit for controlling said power-supply unit and said motor, means connecting said control unit in .controlling relationship with said power-supply unit, means connected to said power-supply uni-t for connecting said power supply unit in arc power-supply relationship with said electrode and said work, means connected to said motor for connecting said arc in energizing relationship with said motor, the last said means including conductors of substantial length extending from said motor terminals to said control unit, a lirst capacitor connected between said conductors near the end thereof adjacent said motor, and a second capacitor of substantially larger capacitance than the capacitance of said irst capacitor connected to said conductors at the ends thereof adjacent said control unit.

4. A drive to be energized either from an alternatingcurrent or a direct-current source, each of said sources having buses, the said drive including a direct-current motor, power supply conductors terminating in a nonpolarized connector to be directly connected to said buses, a rectifier of the bridge type having pairs of opposite rectifier branches, the junctions of which define pairs of opposite conjugate terminals, load conductors of substantial length connected to said motor, means connecting said supply conductors in power-supply relationship with Y one pair of said terminals, means connecting said load conductors in direct-current power deriving relationship with the other pair of said terminals, current iiowing through one pair of said branches when the polarity of said pair is in one sense and current'owing through the other pair of said branches when the polarity of said pair is in the opposite sense, a first capacitor connected between said load conductors adjacent said motor, a second capacitor connected between said load conductors near the end thereof remote from said motor. Y

SApparatusfor arc-welding or arc-melting work with a consumable electrode comprising a welding gun including a motor on said gun for advancing said electrode through said gun, said motor having supply terminals, a power-supply unit for said arc, a control unit for controlling said power-supply unit and said motor, means connecting said control unit in controlling relationship with said power-supply unit, means connected to said power-supply unit for connecting said power-supply unit in arc power supply relationship with said electrode and said work, means connected to said motor Vfor connecting said arc in energizing relationship with said motor, the

last said means including conductors of substantial lengthv extending from said motor terminals to said control unit, and a capacitor having a capacitance of about several hundred microfarads connected to said conductors at the ends thereof adjacent said control unit whereby said lgun and said conductors may be moved relative to said control unit and capacitor. Y

6. Apparatus for welding work with a consumable electrode, said apparatus having a stand-by condition and an operating condition, said work being electrically grounded, the said apparatus including a motor mechanically connected to said electrode to advance said electrode to said work, power-supply conductors to be connected to an alternating supply, a rectilier of the bridge type having conjugate input terminals metallically connected to said conductors and conjugate direct-current output terminals, and control means for said arc and said motor connected between said output terminals and said motor, the said control means including means connected to said motor for connecting said motor electrically to said work during said operating condition, and also includ ing means for maintaining both said conductors disconnected from said work both during said stand-by and during said operating condition.

7. Apparatus for arc-welding or arc melting work with a consumable electrode, said apparatus having a stand-by condition and an operating condition, said work being electrically grounded, the said apparatus including a motor having supply terminals mechanically connected to said electrode to advance` said electrode to said work, power-supply conductors to be connected to an alternating supply, a rectifier of the bridge type having conjugate input terminals connec-ted to said conductors and conjugate output terminals, means connecting one of said motor terminals to a corresponding conjugate output terminal during said :stand-by condition, means connected to said one terminal for maintaining siad one terminal and said corresponding conjugate terminal disconnected from said work during said stand-by condition, and means actuable during the transition of said apparataus from stand-by condition to operating condition for disconnecting said one terminal from said corresponding conjugate terminal and connecting said one terminal to said work.

8. Apparatus for arc-welding or arc-melting work with an electrode, said Work being electrically grounded, control power for said apparatus being derived from a direct or alternating current source having buses at least one of which is grounded, the said apparatus including a control unit for controlling said arc-welding or arc-melting, control power supply means including a bridge rectifier having input and output terminals, means connected to said input terminals for connecting said input terminals metallicallytosaid buses, means connecting said output terminals in power supply relationship with said control unit, means connecting said control unit in controlling relationship with said Work, said control unit including means for setting said apparatus for stand-by and for operation, and means connected to said control unit and to said controlling relationship connecting means for preventing connection of said buses to said work both during stand-by and during operation.

9. Apparatus for arc-welding or arc-melting work withy an electrode, the said apparatus having a stiand-by condition during which it is ready for operation and an operating condition during which said apparatus is in operation arc welding or arc melting work and the said apparatus deriving power for control purposes from power-supply source having buses one of which is electrically hot and the other electrically grounded, and said apparatus including a control unit including power-supply conductors to be connected in power deriving relationship to said buses, and a motor mechanically connected to lsaid electrode for advancing said electrode, means connecting said control unit in energizing relationship with said motor during said stand-by condition, means connected lto said control unit, when actuated for setting said apparatus in oper.- ating condition, for connecting said electrode and work in controlling relationship with said motor, and switch means maintaining both said supply conductors disconnected from said work during said stand-by condition and, responsive to said setting means, for maintaining said motor disconnected from said conductors in said operating condition.

l0. Apparatus for arc-welding or arc-melting work with a consumable electrode, the said apparatus deriving power for control purposes from a power-supply source having buses one of which is electrically hot and another electrically grounded, said Work being electrically grounded, and said apparatus having a stand-by condition and an operating condition, the said apparatus including j a motor connected to said electrode for advancing said electrode, a control unit including power-supply conductors to be connected in power deriving relationship with said motor for energizing said motor during said st'andaby condition, said control unit including lirst switch means closed in said stand-by condition connected to said control unit and said motor connecting said motor to said control unit during said stand-by condition, means connected to said control unit, for setting said electrode and work in arc-Welding relationship during, said operating condition, second switch means open in said stand-by condition for connecting said motor to said electrode and Work during said operating condition, and means responsive to the control unit when it sets said electrode and work in .arc-welding relationship for opening said rst switch means and closing said second switch means, each said rst and second switch means when open maintaining both said supply conductors disconnected from lsaid work.

l1. Apparatus for arc-welding work with a consumable electrode comprising a motor connected to said electrode for advancing said electrode into welding relationship with said work, power supply means for inching said electrode and including a rectifier through which inching power is supplied, means connected to said rectifier and to said work and having `selective settings respectively for selectively connecting said rectifier in electrode-inching relationship with said motor and for connecting said electrode and work in energizing relationship with said motor, and means connected tlo said selective connecting means for disconnecting said work from said rectifier in each of said selective settings.

l2. Apparatus for welding work with a consumable electrode, said apparatus having a stand-by condition and an operating condition, said work being electrically grounded, the said apparatus including a motor mechanically connected to said electrode to advance said electrode to said work, power-supply conductors to be connected to an .alternating supply, one of said supply terminals to be grounded, a rectifier of the bridge type having conjugate input terminals metallically connected to said conductors and conjugate direct-current output terminals, and control means for said arc and said motor connected between said output terminals and said motor, the said control means including means connected to -said motor for connecting said motor metallically to said work during said operating condition, and also including means for maintaining both said conductors disconnected from said work both, during said stand-by and during said operating condition.

References Cited in the le of this patent UNITED STATES PATENTS 1?.. Bascom Aug. 12, 1930 Bousman May 4, 1937 Klnkhamer et a1 Oct. 12, 1948 Busemann July 20, 1954 Flora Oct. 12, 1954 Hackman et al. Sept. 10, 1957 Benz et a1 July 15, 1958 Morley et a1. July 29, 1958 Trousdaie Dec. 30, 1958 Lund Nov. 10, 1959y 

1. APPARATUS FOR ARC WELDING OR ARC MELTING WORK WITH A CONSUMABLE ELECTRODE, COMPRISING A POWER SUPPLY FOR SAID ARC, MEANS CONNECTED TO SAID SUPPLY FOR IMPRESSING A POTENTIAL BETWEEN SAID ELECTRODE AND WORK FOR PRODUCING AN ARC THEREBETWEEN, A MOTOR TO BE CONNECTED TO SAID ELECTRODE FOR ADVANCING SAID ELECTRODE INTO ARC-WELDING RELATIONSHIP WITH SAID WORK, CONDUCTORS OF SUBSTANTIAL LENGTH CONNECTED TO SAID MOTOR FOR CONNECTING SAID ARC IN ENERGIZING RELATIONSHIP WITH SAID MOTOR, A FIRST CAPACITOR CONNECTED BETWEEN SAID CONDUCTORS NEAR THEIR ENDS ADJACENT SAID MOTOR, AND A SECOND CAPACITOR HAVING A CAPACITANCE LARGE COMPARED TO THE CAPACITANCE OF SAID FIRST CAPACITOR CONNECTED BETWEEN SAID CONDUCTORS NEAR THEIR ENDS REMOTE FROM SAID MOTOR. 